1. Technical Field
The present invention relates to a technique of an electro-optical device, such as a liquid crystal device having a touch panel function which allows a user to input various information via a display surface in a manner such that the user points the display surface with a pointing unit, such as a finger, and an electronic apparatus, such as a direct-view display provided with the electro-optical device.
2. Related Art
As for the liquid crystal device which is an example of this kind of the electro-optical device, suggested is a liquid crystal device with a so-called touch panel function, in which optical sensors are arranged for a plurality of pixel portions, respectively, or a plurality of pixel groups, respectively, each pixel group including a certain number of pixel portions, and an image display by transmitted light which passed through the pixel portions and information input to the liquid crystal device via the pointing unit, such as finger, can be realized. In such a liquid crystal device, information input to the liquid crystal device can be realized in a manner such that the pointing unit, such as finger or pointing member, contacts the display surface or moves along the display surface and such contact or movement is detected by an optical sensor.
In the liquid crystal device having a touch panel function, for example, an optical sensor arranged at a region which overlaps the pointing unit, such as finger, of display regions at which an image is displayed, i.e. an optical sensor arranged at an region which overlaps a shadow of the pointing unit detects a light amount of an incident ray, which corresponds to the shadow of the pointing unit. The optical sensor arranged at the region which does not overlap the pointing unit detects a light amount of daylight ray which are not blocked by the pointing unit as the light amount of the incident ray, and acquires an image in which gradation levels are different at portions of the image according to a difference of light amounts. Accordingly, this kind of liquid crystal device detects the light amount of the incident light which is incident from the display surface which displays an image thereon, and can detect a position of the pointing unit on the basis of the image composed of portions of the image with gradation levels specified according to the light amounts of the incident light detected by the optical sensors, respectively. A non-patent document, Touch Panel Function Integrated LCD Using LTPS Technology, N. Nakamura et al, IDW/AD '05 p. 1003-1006, discloses a technique of detecting a position and a waveform of the pointing unit in a manner such that when an intensity of a daylight ray (visible ray) incident onto the display region is strong, a shadow of the pointing unit, such as filter, is detected, but when the intensity of the daylight ray (visible ray) is weak, a reflected ray which is reflected from the pointing unit such as a finger, of rays radiated from the display surface, is detected.
JP-A-2006-301864 discloses a technique of detecting a position of the pointing unit by detecting an infrared ray reflected from the pointing unit in the case in which it is difficult to detect a pointing unit due to relative magnitude relation between an intensity of a daylight ray and an intensity of a display ray radiated from the display surface, when detecting the pointing unit, such as finger.
However, according to technique disclosed in the non-patent document, there is a possibility that, of the display rays, the intensity of the reflected ray reflected from the pointing unit is almost equal to the intensity of the daylight ray under the condition in which the intensity of the display ray radiated from the display surface is almost equal to the intensity of the daylight ray. In such a case, it becomes difficult to differentiate the region overlapping the pointing unit of the display region from the other region on the basis of the difference between the intensities of the reflected ray and the daylight ray, and thus there is a technical problem in which it is difficult to detect the position of the pointing unit.
According to the technique disclosed in JP-A-2006-301864, even though the infrared ray is used to detect the pointing unit, under the condition in which intensities of the reflected infrared ray reflected from the pointing unit, such as a finger, and the infrared ray included in the daylight ray are almost equal to each other, the same problem as in the technique disclosed in the non-patent document occurs.
That is, in the case of detecting the pointing unit, such as a finger, by detecting light having a specific wavelength, there is a possibility that it is difficult to acquire correct information which specifies the position and form of the pointing unit and improve detection sensitivity of detecting the pointing unit according to environment in which the electro-optical device is used.